Papers by Pradeep Awasare
The Aeronautical Journal
The stresses around the passenger door, emergency door and window of an aircraft, Airbus A300B, a... more The stresses around the passenger door, emergency door and window of an aircraft, Airbus A300B, are considered in this paper. By idealising these opening as rectangular holes with rounded corners in an infinite plate subjected to inplane loads and considering the presence of adjacent holes the stresses are determined using the complex variable method along with Schwarz Alternating Method. The results of the analytical solution are found to be in good agreement with those of the finite element analysis using ANSYS 5.0 software within 5%.
Indian Journal of Engineering and Materials Sciences, 1994
The two dimensional elasto-static problem of two unequal arbitrarily oriented elliptical holes su... more The two dimensional elasto-static problem of two unequal arbitrarily oriented elliptical holes subjected to uniform shears is solved in this paper. The problem is formulated in complex plane by using Kolosoff-Muskhelishvili stress functions. The interaction effect of two holes is achieved by use of Schwarz Alternating Method. The sOlution for the problem is obtained up to the third approximation, but it is fo\lnd that the solution converges in second approximation. Ellipse can be made a circle or crack. This leads to various combinations of the geometries for which either stress concentration factor in case of hole or stress intensity factor in case of crack can be obtained from present solution.
SAE International Journal of Commercial Vehicles, 2018
Journal of The Institution of Engineers (India): Series C, 2018
In the present study, a novel method of active vibration control of machines subject to base exci... more In the present study, a novel method of active vibration control of machines subject to base excitation using air spring is proposed. The study also includes proposes of a feedback control system, for active vibration control with mass flow rate as a function of the velocity of the mass, and/or base of air spring. Earlier study shows application of air spring as a force actuator. The mass flow introduces additional input excitation into the system by means of which the stiffness or resultant excitation force on the mass can be changed. A mathematical model is developed and response to steady state and transient base input are obtained. The use of appropriate value of gain in the system can ensure that the amplitude of response to excitation from the base is lower than the amplitude of base excitation. Some suitable values of gain depending on the special cases considered are suggested. An active control system with mass flow rate as a function of base velocity and gain equal to-1 is most effective in controlling the vibration. This is highly desirable in case of high precision equipment. The interesting observation is that the spring rate can be changed and even made negative. Keywords Air spring Á Active vibration control Á Controlled mass flow Á Spring rate Á Pneumatic vibration control Notations A Area of cross section of air spring, m 2 c Damping coefficient of air spring, Ns/m M Mass of the machine, kg P Pressure in the air spring, Pa R Universal gas constant, kJ/kgK-1 T Temperature of air,°K v Volume of air spring, m 3 x Mass displacement (machine displacement), m y Base displacement (ground displacement), m _ m Mass flow rate, kg/s _ p Rate of change of pressure, Pa/s _ x Mass velocity, m/s _ y Base velocity, m/s g 1 Gain for mass flow rate as a function of base velocity g 2 Gain for mass flow rate as a function of mass velocity x n Natural frequency, rad/s c Adiabatic gas constant g Gain for mass flow rate as a function of difference between mass velocity and base velocity n Damping ratio of air spring & Surbhi Razdan
ijcns.com
Laser beam welding is very much popular in Microsystems technology by its precise parameters. Gen... more Laser beam welding is very much popular in Microsystems technology by its precise parameters. Generally it is characterized by transient nature and very short duration of the process. For real-time applications, the model should be computationally efficient and relate critical but unmeasurable variables such as weld bead penetration to easily measurable variables such as the surface temperature. So for accurate real time tracking and inspecting, the wide range of reliable sensor, such as CMOS, CCD, Infrared, Ultra violet and Photodiode based with high performance are extremely demanded in laser welding process. Penetration depth is most important parameter to fulfill the criteria of expected weld bead in laser beam welding. This article describes research review on online measurement techniques is use for identify weld quality (i.e. penetration depth) in real time and control system control the geometry of the weld pool and to prevent defects in laser beam welding.
The problem of interaction of stresses due to the presence of a crack or elliptical hole near a r... more The problem of interaction of stresses due to the presence of a crack or elliptical hole near a rectangular opening in. an infinite plate subjected to uniform stresses at infinity is studied in th is paper. This problem is of importance in a passenger aircraft when a crack is found in the vicinity of the door. The stress concentration factors near the hole and the stress intensity factors near the crack tip are evaluated for various orientations of crack and various lengths and distances of the crack from the hole. In this analysis, the two complex stress function s are found out using Schwarz Alternating Method.
Indian Journal of Engineering and Materials Sciences, 1994
In this paper, a new method is presented which uses Schwarz Alternating technique to determine th... more In this paper, a new method is presented which uses Schwarz Alternating technique to determine the two complex stress functions for the stress field in two dimensional isotropic homogeneous infinite plate with reactangular hole subjected to uniform uniaxial, biaxial, and she~r edge loadings. These stress functions can be reduced to solve various types of hole boundary problems such as circular hole, elliptical hole, square hole and crack. The stress field near the rounded corners of rectangular hole for different angular position of loading are determined. The variation of stress concentration factor with normalized corner radius for various loading oasesare obtained and compared with the existingresults.
International Review of Mechanical Engineering (IREME)
Mechanical Engineering Research, 2016
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ARCHIVE Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science 1989-1996 (vols 203-210)
Application of Impact damper for reduction of vibration amplitude through momentum transfer is no... more Application of Impact damper for reduction of vibration amplitude through momentum transfer is now well established. However, no literature is available for the effect of an impact damper on axial vibration of a rod as a continuous system. The equation for axial vibratory displacement of the rod, fixed at one end and a lumped mass at the other end, is derived by considering steady state vibrations having a period equal to that of the forcing function at the free end. Structural damping is assumed to be modal with a damping ratio of 0.005. Taking this periodicity into account, the repetitive impact force is resolved in the sinusoidal functions through Fourier series analysis. The forcing function thus will have components with the frequency of the external force and the multiple harmonic forces resulting from impacts. Since an infinite series is involved, the solution is obtained for a truncated series using MATLAB. It is observed that the damper is most effective when the Impact distribution parameter is equal to 0.5. The results of the numerical analysis are supported by experiments and are found to be in good agreement with the theoretical results. The reduction of vibration amplitude is observed to be dependent on the clearance (travel of impacting mass), mass ratio of the impacting mass to the main system, frequency of excitation, and the location of the stop in addition to the impact distribution.
In this paper, a study on the vibration of thin cylindrical shells made of a functionally gradien... more In this paper, a study on the vibration of thin cylindrical shells made of a functionally gradient material (FGM) composed of stainless steel and nickel is presented. The effects of the FGM configuration are taken into account by studying the frequencies of two FG cylindrical shells. Type I FG cylindrical shell has nickel on its inner surface and stainless steel on its outer surface and Type II FG cylindrical shell has stainless steel on its inner surface and nickel on its outer surface. The study is carried out based on third order shear deformation shell theory (TSDT). The objective is to study the natural frequencies, the influence of constituent volume fractions and the effects of configurations of the constituent materials on the frequencies. The properties are graded in the thickness direction according to the volume fraction power-law distribution. The analysis is carried out with strains-displacement relations from Love's shell theory. The governing equations are obtained using energy functional with the Rayleigh-Ritz method. Results are presented on the frequency characteristics and the influences of constituent various volume fractions for Type I and II FG cylindrical shells and simply supported boundary conditions on the frequencies.
Indian Journal of Technology
Journal of Vibration and Control, 2014
Particle damping is a passive damping technique in which small metal particles are placed in the ... more Particle damping is a passive damping technique in which small metal particles are placed in the enclosure attached to the vibrating structure at the highest amplitude region. The damping effectiveness of the particle damper has been studied using particle-filled enclosure attached to the free end of a cantilever beam. The optimum size of the single cell enclosure is selected based on experimental analysis and modified as a multiple cell enclosure, which enhances the damping effectiveness. The single cell and multiple cell enclosures are tested keeping the mass of particles constant, which reveals that damping effectiveness is increased significantly using a multiple cell enclosure. A mathematical model has been proposed for a single cell enclosure using the dimensional analysis method. This model is modified for multiple cell enclosure based on a correlation between displacement amplitudes corresponding to resonance for single cell and multiple cell enclosures. It is observed that ...
Waste Management, 2012
A study was conducted to evaluate the leaching potential of unpaved road materials (URM) mixed wi... more A study was conducted to evaluate the leaching potential of unpaved road materials (URM) mixed with lime activated high carbon fly ashes and to evaluate groundwater impacts of barium, boron, copper, and zinc leaching. This objective was met by a combination of batch water leach tests, column leach tests, and computer modeling. The laboratory tests were conducted on soil alone, fly ash alone, and URM-fly ashlime kiln dust mixtures. The results indicated that an increase in fly ash and lime content has significant effects on leaching behavior of heavy metals from URM-fly ash mixture. An increase in fly ash content and a decrease in lime content promoted leaching of Ba, B and Cu whereas Zn leaching was primarily affected by the fly ash content. Numerically predicted field metal concentrations were significantly lower than the peak metal concentrations obtained in laboratory column leach tests, and field concentrations decreased with time and distance due to dispersion in soil vadose zone.
Journal of Vibration and Control, 2014
ABSTRACT
Engineering Fracture Mechanics, 1995
A new fracture initiation criterion is proposed in this paper which agrees with the results obtai... more A new fracture initiation criterion is proposed in this paper which agrees with the results obtained by Theocaris and Andrianopoulos [Engng Fracture Mech.16, 425–432 (1982)] for the case of uniaxial, biaxial and shear loading at infinity. This criterion determines the critical radius and angular location of the crack initiation in the case of ductile materials. The results are in very good agreement with experimental results reported in the literature.
Engineering Fracture Mechanics, 1995
A new fracture initiation criterion is proposed in this paper which agrees with the results obtai... more A new fracture initiation criterion is proposed in this paper which agrees with the results obtained by Theocaris and Andrianopoulos [Engng Fracture Mech.16, 425–432 (1982)] for the case of uniaxial, biaxial and shear loading at infinity. This criterion determines the critical radius and angular location of the crack initiation in the case of ductile materials. The results are in very good agreement with experimental results reported in the literature.
Engineering Fracture Mechanics, 1995
A new fracture initiation criterion is proposed in this paper which agrees with the results obtai... more A new fracture initiation criterion is proposed in this paper which agrees with the results obtained by Theocaris and Andrianopoulos [Engng Fracture Mech.16, 425–432 (1982)] for the case of uniaxial, biaxial and shear loading at infinity. This criterion determines the critical radius and angular location of the crack initiation in the case of ductile materials. The results are in very good agreement with experimental results reported in the literature.
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Papers by Pradeep Awasare